The present invention relates to an automatic accompaniment device for performing automatic accompaniment to generate chord tones and bass tones based on chord designation inputted from a keyboard and an accompaniment pattern stored in a memory.
Conventionally, there is an automatic accompaniment device which memorizes an accompaniment pattern. The device modifies the accompaniment pattern based on performer-played chords, and generates musical tones in accordance with the modified accompaniment pattern to thereby perform an automatic accompaniment. The device can memorize a plurality of accompaniment patterns for different styles or kinds of music compositions such as Rock, Country and so on. The accompaniment pattern is a prescribed sequence of tone generation timing for each constituent note of the chord. The accompaniment pattern contains tone pitch data representing the intervals, from the root, of the constituent notes of a standard chord, for example, C major chord. The tone pitch data addressed by a tempo clock which determines divided time slots within a given measure. When performing an automatic accompaniment the constituent notes of the standard chord is converted into constituent notes of a chord to be performed according to the type and the root note of the chord to be performed. For instance, if accompaniment pattern is recorded or programmed in terms of standard chord C, when chord Dm is detected in the musical instrument, each of constituent note data read from the stored accompaniment pattern is raised uniformly by 2 degrees and further the raised third note is lowered by one semitone interval so as to generate tuned tones. Such method is disclosed in Japanese Patent Application Laid-Open No. 179091/1989. As mentioned above, the accompaniment pattern is built in terms of a particular standard chord, and the conversion of the prescribed pattern is carried out to determine constituent notes of a different chord to be generated. By such a manner, there is no need to prepare different but similar accompaniment patterns for every tonality, thereby advantageously saving a capacity of memory in the device.
However, in the above noted conventional device, the accompaniment pattern represented by interval is uniformly changed solely based on the type of an individually detected chord which is to be reproduced, hence there may be occasionally generated an inconsistent tone of a pitch name which does not match with the tonality of a given music composition.
Referring to FIG. 14, a description is given below for adjustment for an inconsistent pitch tone in case that the accompaniment pattern is with respect to chord C and the tonality of music is tuned to C major key. FIG. 14 is a diagram schematically showing scales in different tonalities of C major, F major, G major and C minor. The accompaniment pattern of chord C is recorded in terms of degrees corresponding to syllable names (Do, Re, Mi, Fa, So, La, Ti) of C major scale. If chord F is detected, the original accompaniment pattern of chord C is converted into that of chord F, such that its, constituent notes are shifted by intervals or actoves corresponding of syllable names of F major scale (Fa, So, La ---). However, F major scale contains a syllable name of Tib (sus4), whereas C major scale does not contain the syllable name of Tib so that generally the note of this syllable name does not match with a given music composition tuned to C major scale, thereby generating an inconsistent tone. Further descriptions will be given later for the G major scale and C minor scale.